The polymerization of monomers using Friedel-Crafts syntheses technique and cationic polymerization frequently require cryogenic polymerization temperatures. In small scale operations, i.e. in laboratories, elaborate dry box systems are desirable together with cryogenic cooling by either an internal or an external heat exchange system. On the other hand, in pilot plant and commercial operations, the equipment required becomes very costly due to the need for refrigeration equipment, external and internal heat exchangers, pumps as well as stirrers. Not only is this apparatus costly and relatively bulky but severe problems are experienced with fouling and plugging of the reactor and stirrers. Although these problems have existed for many decades, little progress has been made in solving the cooling or removal of the heat of polymerization and the fouling, or plugging problems.
The failure of those of ordinary skill or expert in the cryogenic polymerization art to solve these and other problems is amazing when it is understood that the Leidenfrost principle has been known for several decades or longer. Yet, the only utilization thereof known to us was of the type described by J. Roussel, in 1973 in Volume 105 "Chimie et Industre Genie," page 483. Roussel only taught simple reaction systems like the chlorination of ethylene or the nitration of acetanilide. Although Roussel discloses its use in preparing pharmaceuticals from bacterial sources, he further discloses problems were experienced with blockage or plugging the orifices in the nitrogen supply orifice.
In retrospect the failure of those of ordinary skill or those expert in the cryogenic polymerization art to utilize the cheap liquid nitrogen that has been on the market from liquid oxygen plants built to supply oxygen to more modern steel furnaces is amazing.